Socioeconomic status and race are clearly associated with large differences in treatments and outcomes for many health problems, and there is evidence that such disparities are increasing over time. However, the appropriate medical policy response to these disparities is not known, in large part because the factors influencing treatment decisions and the impact of these decisions on outcomes are not well understood. Project 4 will provide new evidence on these questions by examining the relationship between variations in provider, area and policy factors that influence medical practice, and disparities in patient treatments and outcomes. We will: 1. Examine the relationship of physician, hospital and regional characteristics to disparities in treatment. We expect factors that explain disparities will include demographic characteristics of the structural characteristics of the hospital, structural characteristics of the region, characteristics of population served by provider or region, and treatment intensity of the provider or region. 2. Study whether observed differences in health outcomes by race or income can be explained by the differences in treatment patterns. We will examine to what extent disparities are the consequence of where one lives, versus the provider that one is treated by or how one is treated by a given provider. 3. Explore how technological change (and its accompanying impact on scale, scope, and surveillance technology) has influenced trends in health disparities over time. The treatment of most diseases has changed dramatically over time, but little is known about the influence of such changes on treatment disparities, and in turn on trends in health outcomes. 4. Determine the effects of policy changes on treatment and health disparities in the elderly population by focusing on two important areas where there have been significant changes: (a) Medicaid eligibility, and (b) the Disproportionate Share Hospital (DSH) program, both of which increased reimbursements to hospitals serving large disadvantaged populations.